MINOR: debug: let ha_dump_backtrace() dump a bit further for some callers

MINOR: debug: let ha_dump_backtrace() dump a bit further for some callers

The dump state is now passed to the function so that the caller can adjust
the behavior. A new series of 4 values allow to stop *after* dumping main
instead of before it or any of the usual loops. This allows to also report
BUG_ON() that could happen very high in the call graph (e.g. startup, or
the scheduler itself) while still understanding what the call path was.